West Antarctica has warmed by four degrees Fahrenheit since 1958.
That's twice as much as scientists thought, making the area one of the fastest warming in the world.
The findings appear in the journal Nature Geoscience.
The New York Times reports that West Antarctica holds enough ice that, if all melted, could raise sea levels by ten feet or more.
That would not happen for centuries, but even a gradual thaw could cause a threat.